Bottom ports on Peavey Databass and casters

[noam]

I just bought a Peavey Databass combo amp, which has ports on the bottom of about 3" in diameter. In searching for info on this issue, I came across this:

Boundaries or no boundaries the location of the port still doesn't matter, so long as it isn't blocked by placing it within it's own diameter from a wall, or floor in the case of down-firing, or if a rear mounting the port places it at least a quarter wavelength from the baffle, ie., with a cab some four feet or more deep.

posted by Bill Fitzmaurice within another thread. The amp didn't come with casters, so with the rubber feet, the ports are maybe an inch from the floor. Does this mean I should somehow mount the amp higher than at least the diameter of the ports, or is it also fine to leave it as is -- I had heard that the port should either be really close to a wall or floor, or else an appreciable distance. Bill seems to be answering my question in the affirmative (about mounting higher than port diameter), but I'm just wondering what Peavey had in mind, and/or if there is ever a reason to have the ports so close to the floor.

Thanks

[billfitzmaurice]

Originally Posted by noam

I had heard that the port should either be really close to a wall or floor

The port should be less than 1/4 wavelength from the wall and floor; with most cabs that's about four feet. They also should be far enough from the nearest boundary, be it floor or wall, to give a bit of breathing room. Three inches is usually sufficient.

It's possible to engineer a cab with a down-firing port so that the space between the cab and the floor acts as an extension of the port. Doing so allows a substantial reduction in the size of the cab, but also demands that the distance not be altered.
So the question is are the ports down-firing? If so I wouldn't change the distance to the floor. If they're forward or rear firing it doesn't much matter.

[noam]

Thanks, they're down-firing, so it looks like the amp should remain without casters.

[62bass]

Originally Posted by noam

Thanks, they're down-firing, so it looks like the amp should remain without casters.

That amp sounds best and will play pretty loud with the thing sitting on the floor. No riser or casters or putting it on a chair. It doesn't have very much real fundamental bass but you'll be heard very well. Too bad they never made a matching extension cab for it. For its time it was a good little combo.